Objectives: To examine the effect of cannabis policy liberalisation (decriminalisation and legalisation) levels of use in adolescents and young adults. Design: Systematic review and meta-analysis. Inclusion criteria: Included studies were conducted among individuals younger than 25 years and quantitatively assessing consequences of cannabis policy change. We excluded articles: (A) exclusively based on participants older than 25 years; (B) only reporting changes in perceptions of cannabis use; (C) not including at least two measures of cannabis use; (D) not including quantitative data; and (E) reviews, letters, opinions and policy papers. PubMed, PsycINFO, Embase and Web of Science were searched through 1 March 2018. Data extraction and synthesis: Two independent readers reviewed the eligibility of titles and abstracts and read eligible articles, and four authors assessed the risk of bias (Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies). Extracted data were meta-analysed. The protocol was registered with PROSPERO. Results: 3438 records were identified via search terms and four via citation lists; 2312 were retained after removal of duplicates, 99 were assessed for eligibility and 41 were included in our systematic review. 13 articles examined cannabis decriminalisation, 20 examined legalisation for medical purposes and 8 examined legalisation for recreational purposes. Findings regarding the consequences of cannabis decriminalisation or legalisation for medical purposes were too heterogeneous to be meta-analysed. Our systematic review and meta-analysis suggest a small increase in cannabis use among adolescents and young adults following legalisation of cannabis for recreational purposes (standardised mean difference of 0.03, 95% CI −0.01 to –0.07). Nevertheless, studies characterised by a very low/low risk of bias showed no evidence of changes in cannabis use following policy modifications. Conclusions: Cannabis policy liberalisation does not appear to result in significant changes in youths’ use, with the possible exception of legalisation for recreational purposes that requires monitoring. Trial registration number: CRD42018083950.

Objective To assess the effectiveness of a two year exercise programme of progressive balance retraining in reducing injurious falls among women aged 75-85 at increased risk of falls and injuries and living in the community. Design Pragmatic multicentre, two arm, parallel group, randomised controlled trial. Setting 20 study sites in 16 medium to large cities throughout France. Participants 706 women aged 75-85, living in their own home, and with diminished balance and gait capacities, randomly allocated to the experimental intervention group (exercise programme, n=352) or the control group (no intervention, n=354). Intervention Weekly supervised group sessions of progressive balance training offered in community based premises for two years, supplemented by individually prescribed home exercises. Outcome measures A geriatrician blinded to group assignment classified falls into one of three categories (no consequence, moderate, severe) based on physical damage and medical care. The primary outcome was the rate of injurious falls (moderate and severe). The two groups were compared for rates of injurious falls with a “shared frailty” model. Other outcomes included the rates of all falls, physical functional capacities (balance and motor function test results), fear of falling (FES-I), physical activity level, and perceived health related quality of life (SF-36). Analysis was by intention to treat. Results There were 305 injurious falls in the intervention group and 397 in the control group (hazard ratio 0.81, 95% confidence interval 0.67 to 0.99). The difference in severe injuries (68 in intervention group v 87 in control group) was of the same order of magnitude (0.83, 0.60 to 1.16). At two years, women in the intervention group performed significantly better on all physical tests and had significantly better perception of their overall physical function than women in the control group. Among women who started the intervention (n=294), the median number of group sessions attended was 53 (interquartile range 16-71). Five injurious falls related to the intervention were recorded. Conclusion A two year progressive balance retraining programme combining weekly group and individual sessions was effective in reducing injurious falls and in improving measured and perceived physical function in women aged 75-85 at risk of falling. Trial registration ClinicalTrials.gov (NCT00545350).

Cigarette smoking has been identified as a cause of cancer incidence and mortality since the end of World War II¹ and remains a major public health problem today.^2,3 Most smokers initiate tobacco use in adolescence⁴ and attempt to quit at around 30 years of age (especially women) or after 50 years of age.⁵ Pharmacotherapies (nicotine replacement therapy [NRT], bupropion hydrochloride, and varenicline tartrate) and behavioral therapies have been shown to be effective in helping smokers quit.^6-8 However, the appeal of smoking cessation aids is relatively low,⁹ and most quit attempts are done “cold turkey” (ie, stopping nicotine consumption all at once), without professional assistance or treatment,^10-13 which may be because smoking cessation aids have a financial cost or because smokers lack knowledge about their effectiveness and safety. There are also other reasons for not using smoking cessation aids; for example, some smokers believe that quitting without help gives them greater satisfaction and a feeling of self-control, strength, and autonomy.¹⁰ However, studies show that smokers who use smoking cessation aids are more likely to remain abstinent.¹⁴